An Oracle damages expert estimates that Google owes the company US$2.6 billion for alleged Java patent violations, according to a court filing made Tuesday in U.S. District Court for the Northern District of California.

That figure falls in between the "breathtaking" $1.4 billion and $6.1 billion range Google previously cited based on its own interpretation of Oracle expert Iain Cockburn's damages report. Google is seeking to have Cockburn's analysis set aside on grounds it is unreliable.

Oracle sued Google last year, saying its Android mobile operating system violates a number of patents for Java, which Oracle acquired through the purchase of Sun Microsystems. Google has denied any wrongdoing.

"Even the low end of Cockburn's range is over 10 times the amount that Sun Microsystems, Inc. made each year for the entirety of its Java licensing program and 20 times what Sun made for Java-based mobile licensing," Google attorney Scott Weingaertner said in a letter filed earlier this month.

But in its filing Tuesday, Oracle claimed Google relied on a number of "mischaracterizations," thereby attacking "a straw man -- a poor and inaccurate caricature of Prof. Cockburn's report -- rather than the methodology and analysis Prof. Cockburn actually employs."

Cockburn's conclusions are "supported by an abundance of evidence and are reasonable in light of the parties' commercial relationship and the magnitude of the profits at stake," the filing adds.

Oracle is entitled to damages based on a number of grounds, including advertising revenues from Android phones, according to the filing.

Weingaertner rejected the notion in his letter to the court.

"The value of the Android software and of Google's ads are entirely separate: the software allows for phones to function, whether or not the user is viewing ads; and Google's ads are viewable on any software and are not uniquely enabled by Android," he wrote.

Cockburn, who is a professor at Boston University's School of Management, did not immediately respond to a request for comment Tuesday.

"Oracle's 'methodology' for calculating damages is based on fundamental legal errors and improperly inflates their estimates," a Google spokeswoman said in a statement.